Human neutrophil elastase (hereinafter, sometimes referred to as solely “elastase”) is one kind of serine protease having a molecular weight of about 30 KDa and is stored in azurophilic granules of neutrophil. In physiological states, elastase takes, inside of neutrophils, a role for rapid digestion or degradation of phagocytized bacteria or exogenous materials, and takes, outside of neutrophils, roles for degradation of elastin, collagen (type III, type IV), proteoglycan, fibronectin which constitute interstitium of biological connective tissues such as lung, cartilage, blood vessel wall and skin, and for maintenance of tissue homeostasis.
In vivo, endogenous elastase-inhibiting proteins are existed. Among them, best known one is α1-antitrypsin (α1-AT), and patients with genetic defect of α1-AT are known to present chronic obstructive pulmonary disease (COPD) like-symptoms (see Non-Patent Literature-1). Like this case, when an imbalance occurs between endogenous elastase-inhibiting proteins and elastase, or when excess elastase is released due to pathological states such as inflammatory disease, it has been thought that elastase destroys normal tissues actively to cause various pathological conditions.
The diseases in which elastase is suggested to associate with pathological conditions include, for example, chronic obstructive pulmonary disease (COPD), pulmonary cystic fibrosis, emphysema, adult respiratory distress syndrome (ARDS), acute lung injury (ALI), idiopathic interstitial pneumonia (IIP), chronic interstitial pneumonia, chronic bronchitis, chronic airway infection, diffuse panbronchiolitis, bronchiectasis, asthma, pancreatitis, nephritis, hepatic failure, chronic rheumatoid arthritis, arthrosclerosis, osteoarthritis, psoriasis, periodontitis, atherosclerosis, rejection of organ transplantation, premature rupture of membrane, bullosa, shock, sepsis, systemic lupus erythematodes (SLE), Crohn disease, disseminated intravascular coagulation (DIC), ischemia-reperfusion induced-tissue injury, corneal scar tissue formation, myelitis, lung squamous cell carcinoma, pulmonary adenocarcinoma, lung cancers such as non-small cell lung cancer, breast cancer, liver cancer, bladder cancer, colorectal cancer, skin cancer, pancreas cancer, glioma and the others. Thus, an agent showing inhibitory activity for elastase is useful for treatment or prophylaxis of diseases associated with elastase.
With such an expectation, various elastase inhibitors have been reported. For example, Patent Literature-1 discloses 2-pyridone derivatives as neutrophil elastase inhibitor. In claim 1 of the Claims of the Literature, the compounds represented by the following general formula (A-1) (corresponding to formula I of said publication document) are described.

In the formula, variables are defined as follows:
[wherein,
X represents O . . . ;
Y1 represents N . . . ; and when R1 represents OH, Y1 may also, in the tautomeric form, represent NR6;
Y2 represents CR3;
R1 represents . . . , when Y1 represents N, R1 may also represent OH;
. . . ]
If the above-mentioned definitions of X, Y1, Y2 and R1 are assigned to said formula (A-1), the formula (A-1) can be replaced by the following formula (A-2). Here, though there may be the compounds containing uracil backbone, they are clearly different in structure from the present compounds below-mentioned.

Also, as compound showing p38 MAP kinase inhibitory activity, in each claim 1 of the Claims of Patent Literature-2 and Patent Literature-3 the compounds represented by the following general formula (A-3) (corresponding to formula I of said publication documents) are described.
[wherein,
ring A represents a 5-membered mono-ring hetero ring which contains 1 to 3 atom(s) selected from the group consisting of oxygen atom, nitrogen atom and sulfur atom as a hetero atom, and which may have a further substituent(s);
ring B represents an optionally substituted hetero ring containing at least one nitrogen atom;
ring D represents an optionally substituted cyclic group;
ring E represents an optionally substituted cyclic group; and
R1 represents a substituent which contains nitrogen atom(s) having basicity] (see Patent Literature-2); and
[wherein
ring A represents a 5-membered mono-ring hetero ring which contains 1 to 3 atom(s) selected from the group consisting of an oxygen atom, a nitrogen atom and a sulfur atom, and which may have a further substituent(s);
ring B represents a hetero ring which may be substituted and may contain 1 to 3 atom(s) selected from the group consisting of an oxygen atom, a nitrogen atom and a sulfur atom in addition to the described nitrogen atom;
ring D represents a ring group which may be substituted;
ring E represents an optionally substituted cyclic group;
R1 represents a neutral group or an acidic group which contains an oxygen atom(s) and/or a sulfur atom(s)] (see Patent Literature-3).
However, in the compounds described specifically in Patent Literatures-2 and 3, a position of a substituent R1 that is substituted on five membered ring A is a 4th-position counting sequentially from the position binding to ring B, then ring D, while in the present compounds, ring A (corresponding to L of formula (I) described herein) is unsubstituted and a position of a substituent on ring A (corresponding to L of formula (I) described herein) is a 5th-position, which are different each other in structure.